NASA will push ahead with its plan for an October 2009 launch of the already over-budget Mars Science Laboratory despite ongoing technical and schedule difficulties all but certain to push the cost of the mission past $2 billion.

Officials in charge of NASA's Mars program made the announcement Friday following a meeting with NASA Administrator Mike Griffin to discuss what to do about the mission in light of continued cost growth. MSL's price tag has risen $300 million since mid-2006 topping $1.9 billion in NASA's latest public estimate.

Doug McCuistion, the director of NASA's Mars Exploration Program, said MSL will need more than $1.9 billion whether it launches as planned in October 2009 or is delayed two years until the next optimal launch window opens in 2011. McCuistion said NASA was not at liberty to say how much additional money MSL would need until it has a chance to square its budget needs with the White House and Congress.

NASA Mars officials are due to meet with Griffin about MSL again in January. By that time, McCuistion said, MSL officials expect to show that some key hardware and software deliveries holding up the project have been made and that testing has continued to go well.

While NASA could still decide to cancel MSL, NASA's associate administrator for science, Ed Weiler, described that as an unlikely scenario.

"It's easy to say, 'let's just cancel it and move on' but we've poured over a billion-and-half dollars into this," Weiler said. "The science is critical. It's a flagship mission in the Mars program and as long as we think we have a good technical chance to make it we are going to do what we have to do."

Weiler said he would look for additional money for MSL in the Mars budget before putting the pinch on the rest of NASA's planetary science portfolio.